Methods of post treating silicon nitride based dielectric films with high energy low dose plasma

ABSTRACT

A method of post-treating a silicon nitride (SiN)-based dielectric film formed on a surface of a substrate includes positioning a substrate having a silicon nitride (SiN)-based dielectric film formed thereon in a processing chamber, and exposing the silicon nitride (SiN)-based dielectric film to helium-containing high-energy low-dose plasma in the processing chamber. Energy of helium ions in the helium-containing high-energy low-dose plasma is between 1 eV and 3.01 eV, and flux density of the helium ions in the helium-containing high-energy low-dose plasma is between 5×10 15  ions/cm 2 ·sec and 1.37×10 16  ions/cm 2 ·sec.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit to U.S. Provisional Application No.62/858,158, filed Jun. 6, 2019, which is incorporated by referenceherein.

BACKGROUND Field

Embodiments of the present disclosure generally relate to flowablegap-fill films and fabrication processes thereof, and more specifically,to post-treating flowable films by high-energy low-dose plasma.

Description of the Related Art

Fabrication of miniaturized semiconductor devices, including shallowtrench isolation (STI), inter-metal dielectric (IMD) layers, inter-layerdielectric (ILD) layers, pre-metal dielectric (PMD) layers, passivationlayers, fin-field-effective-transistors (FinFET), and the like, faceschallenges in advanced lithography for patterning nano-scaled gatestructures. Silicon nitride is one of primary dielectric materials usedin such structures. Void-free filling of gaps and trenches has beenperformed by flowable chemical vapor deposition (CVD), in whichsilicon-and-nitrogen containing dielectric precursor in a liquid phaseis delivered into gaps and trenches on a substrate (referred to as aflowable film), and then hardened into a silicon nitride (SiN)-baseddielectric film in a solid phase, conventionally by steam annealing,ultraviolet (UV) irradiation, hot pressing, and sintering at hightemperatures. However, such solidification processes are limited to acertain depth within high aspect ratio features and thus the featuresare not fully filled with a silicon nitride (SiN)-based dielectric film.In some instances, flowable films are treated with standard high-densityplasma (HDP) containing high-energy ions to increase the solidificationdepth. However, it is known such HDP treatment does not penetrate into asilicon nitride (SiN)-based dielectric film, and does not increase thesolidification depth to a depth of high aspect ratio features.Therefore, wet etch selectivity of the material within the high aspectratio features (containing silicon nitride partially) over silicon oxideis less than that of silicon nitride over silicon oxide.

Therefore, a new solidification process is needed to form flowable filmsthat fill high aspect ratio gaps and trenches and have improvedmechanical properties, such as an improved wet etch rate (WERR, <2:1),relative to silicon oxide.

SUMMARY

Embodiments described herein generally relate to a method ofpost-treating a silicon nitride (SiN)-based dielectric film formed on asurface of a substrate that includes positioning a substrate having asilicon nitride (SiN)-based dielectric film formed thereon in aprocessing chamber, and exposing the silicon nitride (SiN)-baseddielectric film to helium-containing high-energy low-dose plasma in theprocessing chamber. Energy of helium ions in the helium-containinghigh-energy low-dose plasma is between 1 eV and 3.01 eV, and fluxdensity of the helium ions in the helium-containing high-energy low-doseplasma is between 5×10¹⁵ ions/cm²·sec and 10.37×10¹⁶ ions/cm²·sec.

Embodiments of the disclosure may further provide a method of formingand post-treating a silicon nitride (SiN)-based dielectric film on asurface of a substrate that includes delivering a dielectric precursoronto a substrate disposed in a processing region of a first chamber, thedielectric precursor comprising silicon and nitrogen, providing radicalflux in the processing region of the first chamber, and exposing thedelivered dielectric precursor to helium-containing high-energy low-doseplasma in a second chamber. Energy of helium ions in thehelium-containing high-energy low-dose plasma is between 1 eV and 3.01eV, and flux density of the helium ions in the helium-containinghigh-energy low-dose plasma is between 5×10¹⁵ ions/cm² and 10.37×10¹⁶ions/cm²·sec.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is a flowchart showing a method of forming flowable filmsaccording to one embodiment.

FIG. 2 is a schematic view of a cluster tool according to according toone embodiment.

FIG. 3A is a schematic view of a deposition chamber according to oneembodiment.

FIG. 3B is a schematic bottom view of a shower head according to oneembodiment.

FIG. 4 is a schematic view of a plasma chamber according to oneembodiment.

FIGS. 5A and 5B show optical emission spectroscopy (OES) intensity ofhelium-containing plasma according to one embodiment.

FIG. 6 shows an etch amount of a silicon-nitride (SiN) based dielectricfilm according to one embodiment.

For clarity, identical reference numerals have been used, whereapplicable, to designate identical elements that are common betweenfigures. Additionally, elements of one embodiment may be advantageouslyadapted for utilization in other embodiments described herein.

DETAILED DESCRIPTION

Embodiments described herein provide methods of post-treating a siliconnitride (SiN)-based dielectric film deposited on a substrate, forexample, by flowable chemical vapor deposition (CVD). A silicon nitride(SiN)-based dielectric film contains silicon-nitrogen (Si—N—Si) bonds. Asilicon nitride (SiN)-based dielectric film, as deposited on thesubstrate, may contain a large amount of silicon-hydrogen (Si—H) andnitrogen-hydrogen (N—H) bonds as a result of cross-linking of Si—Hlimited to near a surface of the deposited silicon nitrogen (Si—N)-baseddielectric film, causing insufficient filling of gaps and trenches. Themethods described herein include post-treating a silicon nitride(SiN)-based dielectric film as deposited on a surface of a substrate byexposing the deposited silicon nitride (SiN)-based dielectric film tohelium-containing high-energy low-dose plasma. The methods describedherein can be used to reduce or eliminate Si—H and N—H bonds in siliconnitride (SiN)-based dielectric films to densify the silicon nitride(SiN)-based dielectric film to a large thickness.

Embodiments described herein also provide methods of forming a siliconnitride (SiN)-based dielectric film by flowable CVD to fill gaps andtrenches having high aspect ratio (AR) and small dimensions (e.g.,AR≥8). In some embodiments, silicon nitride (SiN)-based dielectric filmsformed by flowable CVD are seam-free and can fill up high AR gaps andtrenches using a silicon-and-nitrogen dielectric precursor in a liquidphase and radical forms of co-reactants (reactive gas), for example,oxygen (O₂) or ammonia (NH₃).

FIG. 1 is a flowchart illustrating a method 100 that is used to form asilicon nitride (SiN)-based dielectric film on a surface of a substrate,according to one embodiment.

In block 102, a substrate is positioned in a deposition chamber. Asubstrate, for example, may be a metal substrate, such as aluminum orstainless steel, a semiconductor substrate, such as silicon,silicon-on-insulator (SOI), or gallium arsenide, a glass substrate, or aplastic substrate. A semiconductor substrate may be a patternedsubstrate at any stage of manufacture/fabrication in the formation ofintegrated circuits. The patterned substrate may include gaps, trenches,holes, vias, or the like, that are to be filled with dielectricmaterial.

In block 104, one or more dielectric precursors in a liquid phase and acarrier gas, such as argon (Ar) or helium (He), are flowed into thedeposition chamber via a gas delivery device, such as a dual channelshowerhead (DCSH), to deliver the dielectric precursor onto a surface ofthe substrate disposed within the deposition chamber at a flow ratebetween about 250 sccm and about 5000 sccm per channel of the DSCH. Thesurface of the substrate can be held at a reduced temperature of betweenabout 40° C. and about 150° C., for example at about 80° C. A pressureof the deposition chamber may be maintained between about 0.5 Torr andabout 3.0 Torr.

In some embodiments, the dielectric precursor is an organosiliconcompound that includes silicon, nitrogen, hydrogen, and chlorine, suchas silyl-amine and its derivatives including trisilylamine (TSA) anddisilylamine (DSA), an organosilicon compound that includes silicon,nitrogen, hydrogen, and oxygen, or a combination thereof.

In block 106, a plasma may be generated in a remote plasma source (RPS)outside the deposition chamber and flowed into a substrate processingregion of the deposition chamber along with a carrier gas (e.g., Ar,He). The plasma can be generated by the dissociation of a processingprecursor gas including molecular oxygen (O₂), ozone (O₃), molecularhydrogen (H₂), a nitrogen-hydrogen compound (e.g., NH₃, N₂H₄) anitrogen-oxygen compound (e.g., NO, NO₂, N₂O), a hydrogen-oxygencompound (e.g., H₂O, H₂O₂), a nitrogen-hydrogen-oxygen compound (e.g.,NH₄OH), a carbon-oxygen compound (e.g., CO, CO₂), or a combinationthereof. In the plasma, O*, H*, and/or N*-containing radicals may beactivated, such as O*, H*, N*, NH₃*, N₂H₄*, NH₂*, NH*, N*O*, C₃H₆*,C₂H₂*, or a combination thereof.

In some embodiments, the radicals activated in the RPS are flowed intothe deposition chamber (referred to as “radical flux”) at a flow ratebetween about 1 sccm and about 10000 sccm.

In block 108, one or more radicals (also referred to as reactive gas) inthe substrate processing region react with the delivered dielectricprecursor to form a silicon nitride (SiN)-based dielectric film. Thecomposition of the formed silicon nitrogen (Si—N)-based dielectric filmcan be adjusted by changing the composition of the reactive gas in theradical flux. To form a nitrogen-containing film, such as SiON, SiCON,and SiN films, the reactive gas may be, for example, ammonia (NH₃),hydrogen (H₂), hydrazine (N₂H₄), nitrogen dioxide (NO₂), or nitrogen(N₂). When the reactive gas in the substrate processing region reactswith the delivered dielectric precursor, Si—H and N—H bonds (weakerbonds) are partially broken and replaced by Si—N, Si—NH, and/or Si—NH₂bonds (stronger bonds) to form a silicon nitride (SiN)-dielectric film.

In block 110, the formed silicon nitride (SiN)-based dielectric film isexposed to high-energy low-dose plasma containing light ions (i.e.,ionized species having small atomic numbers in the periodic table), suchas helium (He), hydrogen (H₂), argon (Ar), or nitrogen (N₂) in a plasmachamber, to cure the formed silicon nitride (SiN)-based dielectric film.The plasma chamber is coupled to two power sources, an RF power source,which controls density of ion flux (also referred to as ion dose), viainductive coils and a RF power source, which controls ion energy.

The exposure to the light-ion-containing high-energy low-dose plasmacauses further cross-linking between compounds having S—H and N—H bondsin the formed silicon nitride (SiN)-based dielectric film. That is, whenthe S—H and N—H bonds in adjacent compounds in the formed siliconnitride (SiN)-based dielectric film react with the light-ion-containingplasma, the adjacent compounds cross-link by removing S—H bonds andforming Si—N, Si—NH, and/or Si—NH₂ bonds, and thus corresponding portionof the silicon nitride (SiN)-based dielectric film is solidified.

While not intending to be bound by theory, it is believed that radicalsof ions activated in the plasma may physically bombard Si—H bonds withinthe silicon nitride (SiN)-based dielectric film, thereby breaking theSi—H bonds and causing formation of Si—N, Si—NH, and/or Si—NH₂ bonds.The light ions travel through the formed silicon nitride (SiN)-baseddielectric film to a selected depth without substantially damaging theformed silicon nitride (SiN)-based dielectric film. This treatment byradicals of the light ions makes it possible to perform the nitridationprocess (i.e., forming Si—N, Si—NH, and/or Si—NH₂ bonds) withhomogeneity to a depth ranging from 0 nm to 4.2 nm without damaging theformed silicon nitride (SiN)-based dielectric film, while curing by, forexample, thermal annealing or UV irradiation, inevitably is limited tocuring near an exposed surface of the silicon nitride (SiN)-baseddielectric film.

Typically, while not intending to be limiting, the curing the dielectricprecursor (block 110) is performed in a chamber (the plasma chamber)different from the deposition chamber in which the delivery and reactionof the dielectric precursor with the reactive gas (blocks 104-108) areperformed. In general, the set of operations (e.g. blocks 104-108) maybe repeated for multiple cycles to form an overall thicker film.

Embodiments of the deposition systems may be incorporated into largerfabrication systems for producing integrated circuit chips. FIG. 2 showsone such cluster tool 1001 that includes processing chambers 1008 a-f,according to one embodiment. In FIG. 2, a pair of front opening unifiedpods (FOUPs) 1002 supply substrates (e.g., 300 mm diameter wafers) thatare received by robotic arms 1004 and placed into a low pressure holdingarea 1006. A second robotic arm 1010 may be used to transport thesubstrate between the lower pressure holding area 1006 and theprocessing chambers 1008 a-f.

FIG. 3A is a schematic view of a processing chamber 300 having a chamberbody 302 and lid assembly 304, according to one embodiment. The lidassembly 304 generally includes a remote plasma source (RPS) 306, a lid308, and a dual channel showerhead (DCSH) 310. The RPS 306 may process aprocessing precursor gas provided from a processing precursor gas source312. The plasma formed in the RPS 306 may be then delivered through agas inlet assembly 314 and baffle 316, which are coupled to the lid 308,and into a chamber plasma region 318. A carrier gas (e.g., Ar, He) maybe delivered into the chamber plasma region 318. The lid (that is aconductive top portion) 308 and the dual channel showerhead (DCSH) 310are disposed with an insulating ring 320 in between, which allows an ACpotential to be applied to the lid 308 relative to the DCSH 310.

The DCSH 310 is disposed between the chamber plasma region 318 and asubstrate processing region 324 and allows radicals activated in theplasma present within the chamber plasma region 318 to pass through aplurality of through-holes 326 into the substrate processing region 324.The flow of the radicals (radical flux) is indicated by the solid arrows“A” in FIG. 3A. A substrate 328 is disposed on a substrate support 330disposed within the substrate processing region 324. The DCSH 310 alsohas one or more hollow volumes 332 which can be filled with a dielectricprecursor provided from a precursor source 334. The dielectric precursorpasses from the one or more hollow volumes 332 through small holes 336and into the substrate processing region 324, bypassing the chamberplasma region 318. The flow of the dielectric precursor is indicated bythe dotted arrows in FIG. 3A. An exhaust ring 338 is used to uniformlyevacuate the substrate processing region 324 by use of an exhaust pump340. The DCSH 310 may be thicker than the length of the smallestdiameter of the through-holes 326. The length of the smallest diameterof the through-holes 326 may be restricted by forming larger diameterportions of through-holes 326 partially through the DCSH 310, tomaintain a flow of radical flux from the chamber plasma region 318 intothe substrate processing region 324. In some embodiments, the length ofthe smallest diameter of the through-holes 326 may be the same order ofmagnitude as the smallest diameter of the through-holes 326 or less.

In some embodiments, a pair of processing chambers (e.g., 1008 c-d) inFIG. 2 (referred to as a twin chamber) may be used to deposit adielectric precursor on the substrate. Each of the processing chambers(e.g., 1008 c-d) can have a cross-sectional structure of the processingchamber 300 depicted in FIG. 3A. The flow rates per channel of the DCSHdescribed above correspond to flow rates into each of the chambers(e.g., 1008 c-d) via the corresponding DCSH 310.

FIG. 3B is a schematic bottom view of the DCSH 310 according to oneembodiment. The DCSH 310 may deliver via through-holes 326 the radicalflux and the carrier gas present within the chamber plasma region 318.

In some embodiments, the number of through-holes 326 may be betweenabout 60 and about 2000. Through-holes 326 may have round shapes or avariety of shapes. In some embodiments, the smallest diameter ofthrough-holes 326 may be between about 0.5 mm and about 20 mm or betweenabout 1 mm and about 6 mm. The cross-sectional shape of through-holes326 may be made conical, cylindrical or a combination of the two shapes.In some embodiments, a number of small holes 336 may be used tointroduce a dielectric precursor into the substrate processing region324 and may be between about 100 and about 5000 or between about 500 andabout 2000. The diameter of the small holes 336 may be between about 0.1mm and about 2 mm.

FIG. 4 is a schematic view of a plasma chamber 400 having a chamber body402 and lid assembly 404, according to one embodiment. The lid assembly404 includes a gas delivery assembly 406 and a lid 408. The lid 408 hasan opening 410 to allow entrance of one or more processing precursorgases. The gas delivery assembly 406 is disposed over the lid 408through the opening 410. The gas delivery assembly 406 may be connectedto a gas source 412 through a gas inlet 414 to supply one or moreprocessing precursor gases into a substrate processing region 424. Asubstrate 428 is disposed on a substrate support 430 disposed within thesubstrate processing region 424 and coupled to a bias power source (notshown). The one or more processing precursor gases may exit thesubstrate processing region 424 by use of an exhaust ring 438 and anexhaust pump 440.

In the lid assembly 404, inner coils 442, middle coils 444, and outercoils 446 are disposed over the lid 408. The inner cods 442 and theouter cods 446 are coupled to an RF power source 448 through a matchingcircuit 450. Power applied to the outer cods 446 from the RF powersource 448 is inductively coupled through the lid 408 to generate plasmafrom the processing precursor gases provided from the gas source 412within the substrate processing region 424. The RF power source 448 canprovide current at different frequencies to control the plasma density(i.e., number of ions per cc) in the plasma and thus the density of ionflux (ions/cm²-sec). The bias power source controls a voltage betweenthe substrate 428 and the plasma, and thus controls the energy anddirectionality of the ions. Thus, both ion flux and ion energy can beindependently controlled.

A heater assembly 452 may be disposed over the lid 408. The heaterassembly 452 may be secured to the lid 408 by clamping members 454, 456.

The surface of the substrate can be held at a temperature of betweenabout 100° C. and about 400° C. A pressure of the plasma chamber may bemaintained between about 5 mTorr and about 500 mTorr.

In the following, experimental measurements of process parameters usedto process a deposited film are provided as an example to illustrateaspects of the embodiments of the disclosure described herein. Theseexamples are not intended to limit the scope of the present disclosure.

In the experimental measurements, silicon-nitride (SiN)-based dielectricfilms formed according to the method 100 described above were exposed tohelium-containing high-energy low-dose plasma for a time duration ofbetween about 2 minutes and about 3.5 minutes under a pressure ofbetween 15 and 150 mT. The power applied to an electrode disposed withina substrate support by a bias power source (referred to as a bias power)was varied between 100 W and 700 W to vary the energy of helium ions(i.e., ions generated in a plasma) used to bombard the surface of asubstrate due to the applied bias power. The power applied to the RFpower source, which in this example was ICP plasma source, was variedbetween 0 kW and 2.7 kw to vary the density of helium ions generated inthe plasma (i.e., the lower power corresponds to a lower flux density).The formed silicon-nitride (SiN)-based dielectric films were bombardedby the helium ions and densified (i.e., nitrided) to a depth of between2.6 Å and 4.2 Å per cycle and to an overall depth of between 3 nm and4.2 nm. A summary of some of the process parameters that can be used inone or more of the embodiments described herein are summarized below.

Overall nitration Depth (nm) 3-4.2 Ions Helium (He) Flux density(ions/cm² · sec)  5 × 10¹⁵-1.37 × 10¹⁶ Ion energy (eV)  1-3.01 Biaspower (W) 100-700  RF source power (kW) 0-2.7 Pressure (mTorr)  5-300Temperature 100-400  Time (minutes/cycle) 2-3.5

FIG. 5A shows optical emission spectroscopy (OES) intensity of ahelium-containing plasma measured between wavelengths 200 and 900 nm ata power of the RF power source (referred to as a RF source power) of (i)2.7 kW (see line 591) and (ii) 700 W (see line 592). The dominantemission lines in FIG. 5A illustrate the metastable helium (He) atom(e.g., 388.8 nm, 402.6 nm, 447.1 nm, 501.5 nm, 587.5 nm, 667.8 nm, 706.5nm, and 728.1 nm). In addition, the detected reactive species associatedwith nitrogen are excited nitrogen molecules that have an opticalemission spectra wavelength of between 300 and 400 nm. The OES intensitycorresponding to the metastable helium (He) atom in the 700 W RF sourcepower case (see line 591) is about 10 to 1000 times smaller than that inthe 2.7 kW RF source power case (see line 592). Thus, the plasma densityof the helium ion containing plasma is 10 to 1000 times smaller in the700 W RF source power case.

FIG. 5B shows OES intensity of helium-containing plasma at various biaspowers, such as between 100 W and 500 W, and at a pressure 150 mTorr.The RF source power was kept at 0 W, and thus the helium-containingplasma was generated by the application of the bias applied to thesubstrate support electrode. As can be seen from FIG. 5B, the OESintensities corresponding to the dominant emission lines in FIG. 5Aincrease linearly with the applied bias power, and thus with the energyof the helium ions. Thus, in this example, a high-energy low-dose plasmawas provided with a low RF source power (e.g., 700 W) and a high biaspower (e.g., 100-500 W).

The helium-containing plasma, in which the plasma density and the energyof the helium ions can be controlled as described above, can be used todensify the formed deposited layers, such as a silicon-nitride(SiN)-based dielectric film. The helium-containing plasma having a lowplasma density and containing high energy helium ions, which bombard thesubstrate surface, can penetrate deeper within silicon-nitride(SiN)-based dielectric films without creating significant damage to thefilm due to excessive bombardment of the film surface created in higherplasma density processes and the use of higher atomic mass gasestypically used in a conventional plasma processes. The helium-containingplasma having a low plasma density and containing high energy heliumions produce an increased thickness densification in the formedsilicon-nitride (SiN)-based dielectric films with less overall damage.For example, silicon-and-nitride containing flowable films depositedwithin high aspect ratio features can be treated with such high energylow dose helium-containing plasma to densify the flowable film to formsilicon-nitride (SiN) based dielectric films that are densified to anincreased depth within a high aspect ratio feature without significantdamage to the formed flowable film layer.

FIG. 6 shows an amount of a silicon-nitride (SiN)-based dielectric filmremoved using a dilute HF (DHF) solutions prepared by diluting 1% HFwith deionized water for 5 minutes. The silicon-nitride (SiN)-baseddielectric film was formed according to the method 100 described above,and subsequently exposed to helium-containing plasma at a RF sourcepower of 2.7 kW (high dose) and 700 W (low dose), at bias power of 300 W(low energy) and 700 W (high energy), at a pressure of 150 mTorr and 300mTorr. As can be seen in FIG. 6, the lower dose (i.e., at the lower RFsource power) and the higher energy (i.e., at the higher bias power) ofthe helium ions in the plasma increase an etch amount of asilicon-nitride based dielectric film, indicating the formed siliconnitride (SiN)-based dielectric film has nitride (densified) portion to adeeper depth and an etch rate was improved to 12.5 Å/min. A lowerpressure also leads to a higher energy of the helium ions in the plasma,and thus an etch rate was improved.

As described above, post-treating silicon-nitride (SiN)-based flowablefilms with helium-containing high-energy low-dose plasma can increasenitridation depth and improve wet etch rate (WERR) without damaging theflowable films. It should be noted that the particular exampleembodiments described above are only some possible examples of a siliconnitride (SiN)-based dielectric film that can be post-treated byhigh-energy low-dose plasma according to the present disclosure and donot limit the possible configurations, specifications, depositionmethods, or the like of silicon nitride (SiN)-based dielectric films.For example, post-treatment by high-energy low-dose plasma includinglight ions can be applied to any doped or un-doped SiCOH, SiCON, SiO,and SiN films.

While the foregoing is directed to specific embodiments, other andfurther embodiments may be devised without departing from the basicscope thereof, and the scope thereof is determined by the claims thatfollow.

1. A method of post-treating a silicon nitride (SiN)-based dielectricfilm formed on a surface of a substrate, comprising: positioning asubstrate having a silicon nitride (SiN)-based dielectric film formedthereon in a processing chamber; and exposing the silicon nitride(SiN)-based dielectric film to helium-containing high-energy low-doseplasma in the processing chamber, wherein energy of helium ions in thehelium-containing high-energy low-dose plasma is between 1 eV and 3.01eV, and flux density of the helium ions in the helium-containinghigh-energy low-dose plasma is between 5×10¹⁵ ions/cm²·sec and 1.37×10¹⁶ions/cm²·sec.
 2. The method according to claim 1, wherein the siliconnitride (SiN)-based dielectric film comprises S—H bonds.
 3. The methodaccording to claim 1, wherein the silicon nitride (SiN)-based dielectricfilm comprises N—H bonds.
 4. The method according to claim 1, whereinthe substrate is at a temperature between 10° C. and 200° C. during theexposure of the silicon nitride (SiN)-based dielectric film to thehelium-containing high-energy low-dose plasma.
 5. The method accordingto claim 1, wherein the substrate is at a pressure between 15 mTorr and300 mTorr during the exposure of the silicon nitride (SiN)-baseddielectric film to the high density plasma.
 6. The method according toclaim 1, wherein the substrate is made of a material selecting from agroup consisting of metal, semiconductor, and plastic.
 7. A method ofpost-treating a silicon-based film formed on a surface of a substrate,comprising: positioning a substrate having a silicon-based film formedthereon in a processing chamber; and exposing the silicon-based film tohelium-containing high-energy low-dose plasma in the processing chamber,wherein energy of helium ions in the helium-containing high-energylow-dose plasma is between 1 eV and 3.01 eV, and flux density of thehelium ions in the helium-containing high-energy low-dose plasma isbetween 5×10¹⁵ ions/cm²·sec and 1.37×10¹⁶ ions/cm²·sec.
 8. The methodaccording to claim 7, wherein the silicon-based film comprises siliconnitride (SiN).
 9. The method according to claim 7, wherein thesilicon-based film comprises S—H bonds.
 10. The method according toclaim 7, wherein the silicon-based film comprises N—H bonds.
 11. Themethod according to claim 7, wherein the substrate is at a temperaturebetween 10° C. and 200° C. during the exposure of the silicon-based filmto the helium-containing high-energy low-dose plasma.
 12. The methodaccording to claim 7, wherein the substrate is at a pressure between 15mTorr and 300 mTorr during the exposure of the silicon-based film to thehigh density plasma.
 13. The method according to claim 1, wherein thesubstrate is made of a material selecting from a group consisting ofmetal, semiconductor, and plastic.
 14. A method of forming andpost-treating a silicon nitride (SiN)-based dielectric film on a surfaceof a substrate, comprising: delivering a dielectric precursor onto asubstrate disposed in a processing region of a first chamber, thedielectric precursor comprising silicon and nitrogen; providing radicalflux in the processing region of the first chamber; and exposing thedelivered dielectric precursor to helium-containing high-energy low-doseplasma in a second chamber, wherein energy of helium ions in thehelium-containing high-energy low-dose plasma is between 1 eV and 3.01eV, and flux density of the helium ions in the helium-containinghigh-energy low-dose plasma is between 5·10¹⁵ ions/cm²·sec and 1.37·10¹⁶ions/cm²·sec.
 15. The method according to claim 14, wherein thesubstrate is at a temperature between 10° C. and 200° C. during theexposure of the silicon nitride (SiN)-based dielectric film to thehelium-containing high-energy low-dose plasma.
 16. The method accordingto claim 14, wherein the substrate is at a pressure between 15 mTorr and300 mTorr during the exposure of the silicon nitride (SiN)-baseddielectric film to the high density plasma.
 17. The method according toclaim 14, wherein the substrate is made of a material selecting from agroup consisting of metal, semiconductor, and plastic.
 18. The methodaccording to claim 14, wherein the dielectric precursor is anorganosilicon compound that includes silicon, nitrogen, hydrogen, andchlorine.
 19. The method according to claim 14, wherein the dielectricprecursor is an organosilicon compound that includes silicon, nitrogen,hydrogen, and oxygen.
 20. The method according to claim 14, wherein theradical flux comprises radical gas selected from a group consisting ofoxygen (O₂), ozone (O₃), water (H₂O), ammonia (NH₃), hydrazine (N₂H₄),nitrogen dioxide (NO₂), nitrogen (N₂), propylene (C₃H₆), and acetylene(C₂H₂).